hair simulation too slow and cache inaccessible
You should enable Hair Dynamics in order Particle System set to Hair mode to have cache, because


  When set to hair mode, particle system creates only static particles, which may be used for hair, fur...


wiki page.

This type of Particle System may be animated using the cloth solver.

Baking particle system may be neccessary if something happens in the scene, i.e. animation is involved. If dynamic hair is disabled, it seems like hair won't change, so nothing to bake. 

After you enable Hair Dynamics, Particle System will be accessible for baking results and previewing animation when it's played (and so on):